Generally, a magnetic disk device has a magnetic disk that is provided inside a case, a spindle motor that supports and rotates the magnetic disk, a magnetic head that reads data from or writes data on the magnetic disk, and a carriage assembly that supports the magnetic head such that the magnetic head is freely movable with respect to the magnetic disk. The head part of the magnetic head includes a recording head for the writing and a reproducing head for the reading.
One type of a recording head writes data on the magnetic disk perpendicularly to obtain high recording density, high capacity, or a small size. This type of the recording head typically includes a main magnetic pole that generates a perpendicular magnetic field, a write shield magnetic pole that is disposed so as to face the main magnetic pole with a gap, and a coil for causing a magnetic flux to flow in the main magnetic pole.
To further improve the recording density, a recording head of the perpendicular recording type may carries out a microwave-assisted magnetic recording. In such a recording head, a spin torque oscillator which is used as a microwave generator is disposed between a main magnetic pole and a write shield magnetic pole, and a microwave is applied from the spin torque oscillator to the magnetic disk.